When an outgoing call is to be requested on a terminal, the terminal transmits a first outgoing call request containing the priority of outgoing call operation. When the terminal transmits the first outgoing call request, and then receives a second outgoing call request addressed to the terminal before it receives an incoming call response with respect to the first outgoing call request from a destination terminal, the terminal compares the priority contained in the second outgoing call request with the priority contained in the first outgoing call request. The terminal executes an incoming call response procedure corresponding to the second outgoing call request when the priority in the second outgoing call request is higher as the result of comparison between the priorities of outgoing call operation, and executes a outgoing call control following the first outgoing call request when the priority in the first outgoing call request is higher.